Comparing the efficacy of antimicrobial pocket-irrigation protocols in an in vivo breast implant infection model

Background: Breast implant infection and biofilm formation are major concerns in reconstructive and esthetic breast surgery, with significant medical and economic consequences. Staphylococcus is the common pathogen, with rapidly increasing rates of methicillin-resistant Staphylococcus aureus (MRSA). There is no consensus on prevention practices. This study compares the effect of several pocket irrigation and antibiotic prophylaxis regimens on implant colonization and biofilm formation in an established rat model of MRSA-infected silicone breast implants. Methods: Silicone discs were inserted in a sub-pectoral pocket in 57 rats (114 implants). Implant infection was induced by injection of free planktonic MRSA into the surgical pocket. Rats were allocated to study groups treated by different antimicrobial protocols: pocket irrigation with vancomycin, povidone-iodine, or saline. Each group was divided into subgroups treated with or without additional peri-operative systemic vancomycin. Implant colonization or overt infection was assessed at post-operative day 14 both clinically and by cultures. Results: Pocket irrigation with vancomycin prevented contamination in 87% of implants. Irrigation and systemic vancomycin prevented contamination in 100% of implants with no difference between a single preoperative dose and a 48-h regimen. Systemic vancomycin alone or irrigation with povidone-iodine alone resulted in 100% contamination rates. Conclusions: In this in vivo model, combination of systemic vancomycin with vancomycin pocket irrigation was the most effective regimen, preventing contamination in 100% of implants. Continuation of post-operative antibiotic treatment showed no added advantage.